How the Immune System Works

Phagocytosis

One common way your immune system destroys antigens is by phagocytosis. Phagocytosis is the process of engulfing (or “eating”) antigens and releasing enzymes that break down the foreign agent. Some phagocytes, like macrophages, constantly circulate throughout your body, while others remain stationary in certain organs, waiting to be activated. 

Macrophages scavenge for invaders and escalate your immune system’s attack to other white blood cells. When a macrophage consumes an antigen, it displays the antigen to B and T cells so that they, in turn, can initiate an immune response to the foreign agent. For this reason, macrophages are also called antigen-presenting cells. 

Immune Response

When an antigen makes it past your skin, which is your body’s first line of defense, it will be met with a comprehensive attack. First, macrophages recognize the pathogen, engulf it, and secrete chemicals that tell helper T cells to prepare for action. Helper T cells recognize the invader’s shape and chemical signal, and summon other immune cells, like killer T cells and B cells, into action. Killer T cells attack and destroy the antigen, while B cells make antibodies against the invader. The antibodies neutralize the invader or mark them for destruction by other immune cells. When the antigen is gone, suppressor T cells send chemical messengers to T cells and B cells to slow down or stop their activity, thus ending the immune response.

Once a B cell has made an antibody, it presents the antibody to other white blood cells so they can read the blueprint and know which invader to attack. If the same antigen tries to invade your body in the future, your memory B and T cells will recall this antigen and quickly destroy it.